Inactivation mechanism of catalytic infrared against Pseudomonas aeruginosa and its decontamination application on dry green Sichuan pepper (Zanthoxylum schinifolium)

Ferrous sulfate/carboxymethyl chitosan agar-based film triggers ferroptosis in Pseudomonas aeruginosa planktonic and biofilm cells for antibacterial preservation of fruits and vegetables

The ferrous sulfate (FeSO4)-based mechanism causing ferroptosis-like death in Pseudomonas aeruginosa was investigated. FeSO4 triggered ferroptosis in P. aeruginosa planktonic cells, decreased the ratio of glutathione to oxidized glutathione, and resulted in the increase of reactive oxygen species and lipid peroxidation, damaging the integrity of the cell membrane. In addition, FeSO4 prevented P. aeruginosa from forming biofilms on the surface of stainless steel, glass, and high-density polyethylene. Transcriptome analyses indicated that there were 412 up-regulated genes and 782 down-regulated genes following FeSO4 treatment. FeSO4 increased the cross-linking density of a carboxymethyl chitosan (CMCS) agar-based film, reducing its water solubility, swelling degree, water vapor permeability, and oxygen permeability. Finally, FeSO4@CMCS agar-based film showed potential antibacterial ability against the growth of P. aeruginosa in grapes, purple kale, and cherry tomatoes during storage.

Insight into the inhibitory activity and mechanism of bovine cathelicidin BMAP 27 against Salmonella Typhimurium

This study synthesized an antimicrobial peptide based on the bovine cathelicidin BMAP 27 sequence. It was found to have a broad spectrum of antibacterial activity, with exceptionally high activity against Salmonella. However, the antibacterial mechanism of BMAP 27 against Salmonella remains unclear. The minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of BMAP 27 against Salmonella enterica serovar Typhimurium were determined to be 2 μM and 4 μM, respectively. After treatment with 2 MIC of BMAP 27, the absorbance of DNA in centrifugal supernatant increased from 0.244 to 1.464, and that of protein rose from 0.174 to 0.774, respectively. BMAP 27 has compromised the cell membrane as observed through field emission scanning electron microscope (FESEM) and transmission electron microscopy (TEM), and confirmed by the propidium iodide (PI) test. The alkaline phosphatase (AKP) enzyme activity in the supernatant of the 2 MIC treatment group was 2.15 times higher than the control group, indicating extracellular membrane damage. BMAP 27 treatment increased intracellular ROS levels as tested by dichlorofluorescein diacetate (DCFH) staining. DNA interaction analysis revealed that BMAP 27 has a binding affinity towards DNA, causing its characteristic bands to disappear and peak intensity at 260 nm to reduce. Molecular docking identified its potential binding mode with DNA. The crystal violet biofilm staining results demonstrated that BMAP 27 inhibited S. Typhimurium biofilm formation by 43.1 % and cleared mature biofilms by 53.62 %. Confocal Laser scanning electron microscopy (CLSM) observed that BMAP 27 could kill bacteria within the biofilm and dislodge bacteria from the surface of glasses. Swimming tests identified that the motor capacity of S. Typhimurium was diminished by BMAP 27. By counting the total bacteria, BMAP 27 was revealed to exert bacteriostatic effects in chilled pork and orange juice, which might provide a basis for its application in the inhibition of Salmonella.

Research progress in the application of catalytic infrared technology in fruit and vegetable processing

Fruit and vegetable processing can effectively maintain the quality and safety of fruit and vegetable-based products while extending the shelf life of products and saving transportation costs. Infrared (IR) technology has been widely used in many operating units of fruit and vegetable processing because of its versatility of uniform heating, high heat transfer efficiency, and minimized damage to fruit and vegetable tissues. Catalytic IR (CIR), compared to traditional electric IR, is powered by natural gas or liquefied gas, which can improve thermal efficiency while significantly saving energy. However, there is no comprehensive overview discussing and summarizing the utilization and application of the CIR technology in fruit and vegetable processing. Therefore, this review aims to highlight recent advances in the application of CIR technology in fruit and vegetable processing. Specifically, a comprehensive discussion of the physicochemical properties and underlying mechanisms of CIR is provided, and its applications as a single method or in combination with other technologies in fruit and vegetable processes, such as blanching, peeling, microbial population reduction, and drying, are also presented. Besides, the currently used laboratory and pilot-scale equipment of CIR has also been summarized.

Preparation and characterization of oregano essential oil-loaded Dioscorea zingiberensis starch film with antioxidant and antibacterial activity and its application in chicken preservation

In this study, abundant starch was separated from the industrial crop Dioscorea zingiberensis C.H. Wright (DZW), and a novel bioactive packaging film loaded with oregano essential oil (OEO) was prepared and characterized. NaClO solution worked as a bleacher to prepare uniform starch powder from DZW tubers. OEO was selected from among three essential oils of Labiatae family plants for its strongest antibacterial activity. After the addition of OEO into the starch-based film, the UV-vis shielding property and antioxidant activity were enhanced. Meanwhile, the films still have a considerable performance in transparency, mechanical strength and water vapor permeability after incorporated with OEO. Furthermore, the 3% OEO-loaded starch film exhibited the strongest antibacterial activity against Bacillus subtilis, Escherichia coli and Staphylococcus aureus. It effectively lowered the total viable count of fresh chicken under 4 °C preservation conditions. These results revealed that the OEO-loaded DZW starch film can exert a positive effect on maintaining the quality and extending the shelf life of fresh meat. Therefore, readily accessible DZW tubers and oregano are very promising resources for application in degradable bioactive packaging film.